U.S. patent application number 17/468099 was filed with the patent office on 2022-04-28 for backlight unit and display device.
This patent application is currently assigned to LG DISPLAY CO., LTD.. The applicant listed for this patent is LG DISPLAY CO., LTD.. Invention is credited to KiSeong KIM.
Application Number | 20220128866 17/468099 |
Document ID | / |
Family ID | 1000005871557 |
Filed Date | 2022-04-28 |
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United States Patent
Application |
20220128866 |
Kind Code |
A1 |
KIM; KiSeong |
April 28, 2022 |
BACKLIGHT UNIT AND DISPLAY DEVICE
Abstract
A backlight unit and a display device includes a plurality of
light sources and a color conversion layer on a reflective layer,
thereby removing expensive color conversion sheets and supplying
high-quality white light. A backlight unit includes a printed
circuit; light sources on the printed circuit; a reflective layer
on at least a partial area of an area in which the light sources
are not disposed on the printed circuit; a transparent film above
the light sources and the reflective layer and spaced apart from
the light sources and the reflective layer; light diffusion
patterns on at least one of the top and bottom of the transparent
film and corresponding to each of the light sources; a first color
conversion layer on the reflective layer; and a second color
conversion layer on at least one of a top surface and a bottom
surface of the light diffusion patterns.
Inventors: |
KIM; KiSeong; (Paju-si,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG DISPLAY CO., LTD. |
Seoul |
|
KR |
|
|
Assignee: |
LG DISPLAY CO., LTD.
Seoul
KR
|
Family ID: |
1000005871557 |
Appl. No.: |
17/468099 |
Filed: |
September 7, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 1/133606 20130101;
G02F 1/133605 20130101; G02F 1/133614 20210101 |
International
Class: |
G02F 1/1335 20060101
G02F001/1335; G02F 1/13357 20060101 G02F001/13357 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2020 |
KR |
10-2020-0139718 |
Claims
1. A backlight unit, comprising: a printed circuit; a plurality of
light sources disposed on the printed circuit; a reflective layer
disposed on at least a partial area of an area in which the
plurality of light sources are not disposed on the printed circuit;
a transparent film disposed above the plurality of light sources
and the reflective layer and spaced apart from the plurality of
light sources and the reflective layer; a plurality of light
diffusion patterns disposed on at least one of the top and bottom
of the transparent film and corresponding to each of the plurality
of light sources; a first color conversion layer disposed on the
reflective layer; and a second color conversion layer disposed on
at least one of a top surface and a bottom surface of the plurality
of light diffusion patterns.
2. The backlight unit of claim 1, wherein each of the plurality of
light sources is disposed inside a hole in which the reflective
layer is not disposed on the printed circuit, and the first color
conversion layer having a pattern surrounding the hole.
3. The backlight unit of claim 2, wherein the pattern of the first
color conversion layer is a pattern comprising two or more rings
surrounding the hole, and at least a portion of the reflective
layer is exposed between the two or more rings, and a width of a
ring close to the hole is greater than a width of a ring far from
the hole.
4. The backlight unit of claim 2, wherein the pattern is a radial
dot pattern centered on the light source, and a size of the dot
close to the hole is larger than a size of the dot far from the
hole.
5. The backlight unit of claim 1, wherein the second color
conversion layer comprises a center pattern filled inside and a
peripheral pattern surrounding the center pattern.
6. The backlight unit of claim 5, wherein the peripheral pattern is
a ring pattern surrounding the center pattern.
7. The backlight unit of claim 5, wherein the peripheral pattern is
a pattern comprising a plurality of dots surrounding the center
pattern, and the size of each of the plurality of dots is smaller
than the size of the center pattern.
8. The backlight unit of claim 1, wherein the first color
conversion layer comprises: a plurality of phosphors that are
excited by light emitted from the plurality of light sources to
emit light of different wavelengths; and a resin in which the
plurality of phosphors are mixed, and the first color conversion
layer is patterned on the reflective layer.
9. The backlight unit of claim 1, wherein the second color
conversion layer comprises: a plurality of phosphors that are
excited by light emitted from the plurality of light sources to
emit light of different wavelengths; and a resin in which the
plurality of phosphors are mixed, and the second color conversion
layer is patterned on at least one of the plurality of light
diffusion patterns and a top surface and a bottom surface of the
transparent film.
10. A backlight unit comprising: a printed circuit; a plurality of
light sources disposed on the printed circuit; a transparent film
disposed above the plurality of light sources and spaced apart from
the plurality of light sources; a plurality of light diffusion
patterns disposed on at least one of the top and bottom of the
transparent film and corresponding to each of the plurality of
light sources; a first color conversion layer disposed on at least
a partial area among an area at which the plurality of light
sources are not disposed; and a second color conversion layer
disposed on at least one of a top surface and a bottom surface of
the plurality of light diffusion patterns.
11. A display device comprising: a display panel; and a backlight
unit to supply light to the display panel, wherein the backlight
unit comprises a printed circuit, a plurality of light sources
disposed on the printed circuit, a transparent film disposed on the
plurality of light sources and spaced apart from the plurality of
light sources, a plurality of light diffusion patterns disposed on
at least one of the top and bottom of the transparent film and
corresponding to each of the plurality of light sources, a first
color conversion layer disposed on at least a partial area among an
area at which the plurality of light sources are not disposed, and
a second color conversion layer disposed on at least one of a top
surface and a bottom surface of the plurality of light diffusion
patterns.
12. The display device of claim 11, wherein the backlight unit
further comprises a reflective layer disposed on at least a partial
area of an area in which the plurality of light sources are not
disposed on the printed circuit, the transparent film is disposed
on the reflective layer and spaced apart from the reflective layer,
and the first color conversion layer is disposed on the reflective
layer.
13. The display device of claim 12, wherein each of the plurality
of light sources is disposed inside a hole in which the reflective
layer is not disposed on the printed circuit, and the first color
conversion layer having a pattern surrounding the hole.
14. The display device of claim 13, wherein the pattern of the
first color conversion layer is a pattern comprising two or more
rings surrounding the hole, and at least a portion of the
reflective layer is exposed between the two or more rings, and a
width of a ring close to the hole is greater than a width of a ring
far from the hole.
15. The display device of claim 13, wherein the pattern is a radial
dot pattern centered on the light source, and a size of the dot
close to the hole is larger than a size of the dot far from the
hole.
16. The display device of claim 12, wherein the second color
conversion layer comprises a center pattern filled inside and a
peripheral pattern surrounding the center pattern.
17. The display device of claim 16, wherein the peripheral pattern
is a ring pattern surrounding the center pattern.
18. The display device of claim 16, wherein the peripheral pattern
is a pattern comprising a plurality of dots surrounding the center
pattern, and the size of each of the plurality of dots is smaller
than the size of the center pattern.
19. The display device of claim 12, wherein the first color
conversion layer comprises: a plurality of phosphors that are
excited by light emitted from the plurality of light sources to
emit light of different wavelengths; and a resin in which the
plurality of phosphors are mixed, and the first color conversion
layer is patterned on the reflective layer.
20. The display device of claim 12, wherein the second color
conversion layer comprises: a plurality of phosphors that are
excited by light emitted from the plurality of light sources to
emit light of different wavelengths; and a resin in which the
plurality of phosphors are mixed, and the second color conversion
layer is patterned on at least one of the plurality of light
diffusion patterns and a top surface and a bottom surface of the
transparent film.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to Korean Patent
Application No. 10-2020-0139718, filed on Oct. 26, 2020 in the
Republic of Korea, which is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a backlight unit and a
display device.
DISCUSSION OF THE RELATED ART
[0003] With the development of the information society, there has
been an increasing demand for a variety of types of display
devices. In this regard, various display devices, such as liquid
crystal display (LCD) devices, and organic light-emitting diode
(OLED) display devices, have recently come into widespread use.
[0004] Among such display devices, the liquid crystal display
device may include a display panel and a backlight unit supplying
light to the display panel. In addition, the display panel
receiving light from the backlight unit may adjust the brightness
of the subpixels disposed on the display panel and display an image
corresponding to an image data.
[0005] In addition, when the backlight unit excites light of a
specific wavelength band to supply white light, low light
efficiency may increase power consumption or increase the
manufacturing cost of the backlight unit, thereby being many
difficulties to realize high luminance.
SUMMARY
[0006] Accordingly, embodiments of the present disclosure are
directed to a backlight unit and a display device that
substantially obviates one or more of the problems due to
limitations and disadvantages of the related art.
[0007] An aspect of the present disclosure is to provide a
backlight unit and a display device to improve halo
characteristics.
[0008] Another aspect of the present disclosure is to provide a
backlight unit and a display device to improve uniformity of white
light emitted from a top surface thereof.
[0009] Additional features and aspects will be set forth in the
description that follows, and in part will be apparent from the
description, or may be learned by practice of the inventive
concepts provided herein. Other features and aspects of the
inventive concepts may be realized and attained by the structure
particularly pointed out in the written description, or derivable
therefrom, and the claims hereof as well as the appended
drawings.
[0010] To achieve these and other aspects of the inventive
concepts, as embodied and broadly described herein, a backlight
unit comprises a printed circuit, a plurality of light sources
disposed on the printed circuit, a reflective layer disposed on at
least a partial area of an area in which the plurality of light
sources are not disposed on the printed circuit, a transparent film
disposed above the plurality of light sources and the reflective
layer and spaced apart from the plurality of light sources and the
reflective layer, a plurality of light diffusion patterns disposed
on at least one of the top and bottom of the transparent film and
corresponding to each of the plurality of light sources, a first
color conversion layer disposed on the reflective layer, and a
second color conversion layer disposed on at least one of a top
surface and a bottom surface of the plurality of light diffusion
patterns.
[0011] In another aspect, a backlight unit comprises a printed
circuit, a plurality of light sources disposed on the printed
circuit, a transparent film disposed above the plurality of light
sources and spaced apart from the plurality of light sources, a
plurality of light diffusion patterns disposed on at least one of
the top and bottom of the transparent film and corresponding to
each of the plurality of light sources, a first color conversion
layer disposed on at least a partial area among an area at which
the plurality of light sources are not disposed, and a second color
conversion layer disposed on at least one of a top surface and a
bottom surface of the plurality of light diffusion patterns.
[0012] In another aspect, a display device comprises a display
panel, and a backlight unit to supply light to the display panel.
The backlight unit includes a printed circuit, a plurality of light
sources disposed on the printed circuit, a transparent film
disposed on the plurality of light sources and spaced apart from
the plurality of light sources, a plurality of light diffusion
patterns disposed on at least one of the top and bottom of the
transparent film and corresponding to each of the plurality of
light sources, a first color conversion layer disposed on at least
a partial area among an area at which the plurality of light
sources are not disposed, and a second color conversion layer
disposed on at least one of a top surface and a bottom surface of
the plurality of light diffusion patterns.
[0013] According to exemplary aspects, a backlight unit and a
display device may improve the halo characteristics.
[0014] According to exemplary aspects, a backlight unit and a
display device may improve uniformity of white light emitted from a
top surface thereof.
[0015] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the inventive concepts as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings, which are included to provide a
further understanding of the disclosure and are incorporated in and
constitute a part of this application, illustrate embodiments of
the disclosure and together with the description serve to explain
various principles. In the drawings:
[0017] FIG. 1 illustrates a schematic configuration of a display
device according to embodiments.
[0018] FIGS. 2 and 3 illustrate examples of the cross-sectional
structure of a backlight unit included in a display device
according to embodiments of the present disclosure.
[0019] FIG. 4 illustrates a structure in which white light is
emitted to a top surface of a backlight unit of FIG. 2.
[0020] FIGS. 5A to 5C illustrates a first color conversion layer of
a backlight unit according to embodiments of the present
disclosure.
[0021] FIGS. 6A to 6C illustrates a second color conversion layer
of a backlight unit according to embodiments of the present
disclosure.
[0022] FIG. 7 illustrates another example of a structure of a
backlight unit included in the display device according to
embodiments of the present disclosure.
DETAILED DESCRIPTION
[0023] In the following description of examples or embodiments of
the present disclosure, reference will be made to the accompanying
drawings in which it is shown by way of illustration specific
examples or embodiments that can be implemented, and in which the
same reference numerals and signs can be used to designate the same
or like components even when they are shown in different
accompanying drawings from one another. Further, in the following
description of examples or embodiments of the present invention,
detailed descriptions of well-known functions and components
incorporated herein will be omitted when it is determined that the
description may make the subject matter in some embodiments of the
present invention rather unclear. The terms such as "including",
"having", "containing", "constituting" "make up of", and "formed
of" used herein are generally intended to allow other components to
be added unless the terms are used with the term "only". As used
herein, singular forms are intended to include plural forms unless
the context clearly indicates otherwise.
[0024] Terms, such as "first", "second", "A", "B", "(A)", or "(B)"
may be used herein to describe elements of the present invention.
Each of these terms is not used to define essence, order, sequence,
or number of elements etc., but is used merely to distinguish the
corresponding element from other elements.
[0025] When it is mentioned that a first element "is connected or
coupled to", "contacts or overlaps" etc. a second element, it
should be interpreted that, not only can the first element "be
directly connected or coupled to" or "directly contact or overlap"
the second element, but a third element can also be "interposed"
between the first and second elements, or the first and second
elements can "be connected or coupled to", "contact or overlap",
etc. each other via a fourth element. Here, the second element may
be included in at least one of two or more elements that "are
connected or coupled to", "contact or overlap", etc. each
other.
[0026] When time relative terms, such as "after," "subsequent to,"
"next," "before," and the like, are used to describe processes or
operations of elements or configurations, or flows or steps in
operating, processing, manufacturing methods, these terms may be
used to describe non-consecutive or non-sequential processes or
operations unless the term "directly" or "immediately" is used
together.
[0027] In addition, when any dimensions, relative sizes etc. are
mentioned, it should be considered that numerical values for an
elements or features, or corresponding information (e.g., level,
range, etc.) include a tolerance or error range that may be caused
by various factors (e.g., process factors, internal or external
impact, noise, etc.) even when a relevant description is not
specified. Further, the term "may" fully encompasses all the
meanings of the term "can".
[0028] Hereinafter, exemplary aspects will be described in detail
with reference to the accompanying drawings.
[0029] FIG. 1 illustrates a schematic configuration of a display
device 100 according to embodiments of the present disclosure. All
the components of the display device 100 according to all
embodiments of the present disclosure are operatively coupled and
configured.
[0030] Referring to FIG. 1, the display device 100 according to the
embodiments of the present disclosure can comprise a display panel
110 including an active area A/A where a plurality of subpixels SP
are disposed and a non-active area N/A which is disposed outside
the active area A/A. Furthermore, the display device 100 can
comprise a gate driving circuit 120, a data driving circuit 130,
and a controller 140 for driving the display panel 110.
[0031] A plurality of gate lines GL and a plurality of data lines
DL can be arranged on the display panel 110, and the plurality of
subpixels SP can be disposed in the areas where the gate lines GL
and the data lines DL intersect each other.
[0032] The gate driving circuit 120 is controlled by the controller
140, and sequentially outputs scan signals to a plurality of gate
lines GL arranged on the display panel 110, thereby controlling the
driving timing of a plurality of subpixels SP.
[0033] The gate driving circuit 120 can comprise one or more gate
driver integrated circuits GDIC, and can be disposed only at one
side of the display panel 110, or can be disposed at both sides
thereof according to a driving method.
[0034] Each gate driver integrated circuit GDIC can be connected to
a bonding pad of the display panel 110 by a tape automated bonding
TAB method or a chip-on-glass COG method, or can be implemented by
a gate-in-panel GIP method to then be directly arranged on the
display panel 110. In some cases, the gate driver integrated
circuit GDIC can be integrated and arranged on the display panel
110. In addition, each gate driver integrated circuit GDIC can be
implemented by a chip-on-film COF method in which an element is
mounted on a film connected to the display panel 110.
[0035] The data driving circuit 130 receives image data Data from
the controller 140 and converts the image data Data into an analog
data voltage. Then, the data driving circuit 130 outputs the data
voltage to each data line DL according to the timing at which the
scan signal is applied through the gate line GL so that each of the
plurality of subpixels SP emits light having brightness according
to the image data.
[0036] The data driving circuit 130 can comprise one or more source
driver integrated circuits SDIC.
[0037] Each source driver integrated circuit SDIC can comprise a
shift register, a latch circuit, a digital-to-analog converter, an
output buffer, and the like.
[0038] Each source driver integrated circuit SDIC can be connected
to a bonding pad of the display panel 110 by a tape automated
bonding TAB method or a chip-on-glass COG method, or can be
directly disposed on the display panel 110. Alternatively, in some
cases, the source driver integrated circuit SDIC can be integrated
and arranged on the display panel 110. In addition, each source
driver integrated circuit SDIC can be implemented by a chip-on-film
COF method in which each source driver integrated circuit SDIC can
be mounted on a film connected to the display panel 110, and can be
electrically connected to the display panel 110 through wires on
the film.
[0039] The controller 140 supplies various control signals to the
gate driving circuit 120 and the data driving circuit 130, and
controls the operation of the gate driving circuit 120 and the data
driving circuit 130.
[0040] The controller 140 can be mounted on a printed circuit
board, a flexible printed circuit, or the like, and can be
electrically connected to the gate driving circuit 120 and the data
driving circuit 130 through the printed circuit board, the flexible
printed circuit, or the like.
[0041] The controller 140 allows the gate driving circuit 120 to
output a scan signal according to the timing implemented in each
frame, and converts a data signal received from the outside to
conform to the data signal format used in the data driving circuit
130 and then outputs the converted image data to the data driving
circuit 130.
[0042] The controller 140 receives, from the outside (e.g., a host
system), various timing signals including a vertical
synchronization signal VSYNC, a horizontal synchronization signal
HSYNC, an input data enable DE signal, a clock signal CLK, and the
like, as well as the image data.
[0043] The controller 140 can generate various control signals
using various timing signals received from the outside, and can
output the control signals to the gate driving circuit 120 and the
data driving circuit 130.
[0044] For example, in order to control the gate driving circuit
120, the controller 140 outputs various gate control signals GCS
including a gate start pulse GSP, a gate shift clock GSC, a gate
output enable signal GOE, or the like.
[0045] The gate start pulse GSP controls operation start timing of
one or more gate driver integrated circuits GDIC constituting the
gate driving circuit 120. The gate shift clock GSC, which is a
clock signal commonly input to one or more gate driver integrated
circuits GDIC, controls the shift timing of a scan signal. The gate
output enable signal GOE specifies timing information on one or
more gate driver integrated circuits GDIC.
[0046] In addition, in order to control the data driving circuit
130, the controller 140 outputs various data control signals DCS
including a source start pulse SSP, a source sampling clock SSC, a
source output enable signal SOE, or the like.
[0047] The source start pulse SSP controls a data sampling start
timing of one or more source driver integrated circuits SDIC
constituting the data driving circuit 130. The source sampling
clock SSC is a clock signal for controlling the timing of sampling
data in the respective source driver integrated circuits SDIC. The
source output enable signal SOE controls the output timing of the
data driving circuit 130.
[0048] The display device 100 can further comprise a power
management integrated circuit for supplying various voltages or
currents to the display panel 110, the gate driving circuit 120,
the data driving circuit 130, and the like or controlling various
voltages or currents to be supplied thereto.
[0049] Each of the plurality of subpixels SP can be an area defined
by the intersection of the gate line GL and the data line DL, and a
liquid crystal or a light-emitting element can be disposed therein
depending on the type of the display device 100.
[0050] For example, in the case that the display device 100 is a
liquid crystal display device, the display device 100 can comprise
a light source device such as a backlight unit 200 for emitting
light to the display panel 110, and a liquid crystal can be
disposed in the subpixel SP of the display panel 110. In addition,
since the arrangement of the liquid crystal is adjusted by the
electric field produced due to the data voltage applied to each
subpixel SP, the brightness according to image data can be
realized, thereby displaying images.
[0051] FIGS. 2 and 3 illustrate examples of the cross-sectional
structure of a backlight unit included in a display device
according to embodiments of the present disclosure.
[0052] Referring to FIGS. 2 and 3, a backlight unit 200 according
to embodiments of the present disclosure may include a cover bottom
210 for accommodating light-emitting elements included in the
backlight unit 200.
[0053] A printed circuit 230 may be attached to an adhesive tape
220 on the cover bottom 210. The printed circuit 230 may be
disposed on the cover bottom 210 without the adhesive tape 220 or
other element.
[0054] The printed circuit 230 may be in the form of a substrate.
In addition, the printed circuit 230 may be a printed circuit board
PCB, a flexible printed circuit board FPCB, a glass substrate, and
the like.
[0055] A plurality of light sources 300 may be disposed on the
printed circuit 230. The plurality of light sources 300 may be
light-emitting diodes LEDs, and may be light-emitting diodes LEDs
that emit light of a specific wavelength band. The plurality of
light sources 300 may be various light sources such as organic
light-emitting diodes OLEDs.
[0056] The light source 300 on the printed circuit 230 may include
a light emitting portion 310 and an electrode portion 320 for
driving the light emitting portion 310. The light emitting portion
310 of the light source 300 may include an n-type semiconductor
layer, an activation layer, and a p-type semiconductor layer.
[0057] A reflective layer 400 may be disposed on at least a partial
area of an area in which the plurality of light sources 300 are not
disposed on the printed circuit 230. The reflective layer 400
includes a plurality of holes 325, and the light source 300 may be
disposed in each of the plurality of holes 325. The holes 325 may
have various shapes, such as a circle or a square. Hereinafter, the
hole 325 is described as being a circular hole, but is not limited
thereto.
[0058] The light source protection unit 240 may be disposed on the
plurality of light sources 300 and the reflective layer 400. The
light source protection unit 240 may protect the plurality of light
sources 300 from external force and may diffuse light emitted from
the light source 300.
[0059] That is, the light source protection unit 240 provides a
function of protecting the light source 300 from external impact
while covering the light source 300, or a light guide function that
diffuses the light emitted from the light source 300 in the
backlight unit 200. The light source protection unit 240 may be
made of various materials such as a transparent resin.
[0060] A transparent film 250 may be disposed above the light
source protection unit 240, and a plurality of light blocking
patterns 260 may be disposed above or below the transparent film
250.
[0061] The plurality of light blocking patterns 260 may be disposed
on the light source protection unit 240 at positions corresponding
to the plurality of light sources 300 on the printed circuit 230.
In other words, the plurality of light blocking patterns 260 may be
disposed at a position corresponding to the light source 300 on the
transparent film 250 or may be disposed at a position corresponding
to the light source 300 under the transparent film 250. In
addition, the plurality of light blocking patterns 260 may be
disposed at positions corresponding to the holes 325 in which the
plurality of light sources 300 are disposed.
[0062] The light blocking pattern 260 may reflect, scatter, or
diffract some of the light emitted from the plurality of light
sources 300. That is, since the light blocking pattern 260 is
disposed in an area having the strongest light intensity, a
difference in luminance between an area in which the light source
is disposed and an area in which the light source is not disposed
may be reduced. The light blocking pattern 260 may be a light
diffusion pattern that provides a light diffusion function.
[0063] A diffusion plate 280 for diffusing light incident from the
bottom may be disposed on the transparent film 250.
[0064] An optical sheet 290 having light condensing and light
guiding functions may be disposed on the diffusion plate 280.
[0065] A color conversion layer 500 that is excited by light
emitted from a plurality of light sources 300 and emits light of a
long wavelength may be disposed between the reflective layer 400
and the diffusion plate 280. In addition, the color conversion
layer 500 includes a first color conversion layer 510 disposed on
the reflective layer 400 and a second color conversion layer 520
disposed in a area corresponding to a plurality of light blocking
patterns 260 on the transparent film 250 or under the transparent
film 250. In addition, the light source protection unit 240 may be
disposed on the first color conversion layer 510, and the light
source protection unit 240 may be disposed below the second color
conversion layer 520.
[0066] In other words, the first color conversion layer 510 may be
disposed between the reflective layer 400 and the light source
protection unit 240, and the second color conversion layer 520 is
spaced apart from the first color conversion layer 510 and may be
disposed in an area corresponding to the plurality of light
blocking patterns 260. Accordingly, the second color conversion
layer 520 may be disposed on a substantially vertical line from the
light source 300.
[0067] The color conversion layer 500 may be, for example, a resin
ink layer including a plurality of KSF phosphors. For example, the
first color conversion layer 510 may convert a part of light
reflected in the direction of the top surface of the reflective
layer 400 into light of a different wavelength. For example, when
the light source 300 is a blue LED, the first color conversion
layer 510 may include a phosphor for converting incident light into
red light and green light. The second color conversion layer 520
may include a phosphor for converting incident light into red light
and green light. Alternatively, the first color conversion layer
510 may include a phosphor for converting incident light into red
light, and the second color conversion layer 520 may include a
phosphor for converting incident light into green light.
Conversely, the first color conversion layer 510 may include a
phosphor for converting incident light into green light, and the
second color conversion layer 520 may include a phosphor for
converting incident light into red light. Accordingly, the
backlight unit 200 may emit white light.
[0068] The first color conversion layer 510 may be formed, for
example, by patterning a resin including a phosphor on the
reflective layer 400. In addition, the second color conversion
layer 520 may be formed, for example, by sequentially patterning
the light blocking pattern 260 and the second color conversion
layer 520 on the transparent film 250. Conversely, after first
patterning the second color conversion layer 520 on the transparent
film 250, the light blocking pattern 260 may be disposed on the
second color conversion layer 520.
[0069] In the present disclosure, the first color conversion layer
510 is disposed on the reflective layer 400, and the second color
conversion layer 520 is disposed on or below the plurality of light
blocking patterns 260, thereby providing the backlight unit 200
capable of increasing color conversion efficiency and supplying
white light even without a separate color conversion sheet.
[0070] And, since the backlight unit 200 according to the present
disclosure includes the color conversion layer 500 and does not
include a color conversion sheet, thereby alleviating the problem
of light emitted from the plurality of light sources 300 being
reflected by the color conversion sheet and out of the local
dimming area.
[0071] In other words, the backlight unit 200 according to the
present disclosure disposes the color conversion layer 500 adjacent
to the plurality of light sources 300, thereby alleviating the Halo
characteristic with which light is emitted outside the local
dimming area.
[0072] An adhesive layer 270 is disposed on one surface of the
transparent film 250. The adhesive layer 270 may have a function of
bonding the transparent film 250 and the light source protection
unit 240.
[0073] The adhesive layer 270 may be disposed in an area where the
plurality of light blocking patterns 260 are not disposed, or may
be disposed to cover at least a portion of the plurality of light
blocking patterns 260, or completely cover all of the plurality of
light blocking patterns 260.
[0074] FIG. 4 illustrates a state in which a backlight unit 200
according to embodiments of the present invention emits white
light.
[0075] Referring to FIG. 4, the light source 300 emitting blue
light is disposed on the printed circuit 230. The light blocking
pattern 260 and the second color conversion layer 520 is disposed
under the transparent film 250. The first color conversion layer
510 is disposed on the top surface of the reflective layer 400.
[0076] Some of the light (A) emitted from the light source 300 may
pass through the light blocking pattern 260 and be emitted to the
top surface of the backlight unit 200. In addition, some of the
rest of the light (B) emitted from the light source 300 may be
reflected to the top surface of the reflective layer 400 by the
light blocking pattern 260.
[0077] Accordingly, some of the light (A) emitted from the light
source 300 may be converted in wavelength while passing through the
second color conversion layer 520, and the white light may be
emitted to the top of the backlight unit 200.
[0078] In addition, some of the rest of the light (B) emitted from
the light source 300 may be reflected by the light blocking pattern
260 and reflected to the top surface of the reflective layer 400.
That is, some of the rest of the light (B) emitted from the light
source 300 may be color converted by the second color conversion
layer 520 on the bottom surface of the light blocking pattern 260
or the first color conversion layer 510 on the top surface of the
reflective layer 400. In other words, some of the rest of the light
(B) emitted from the light source 300 may be converted in
wavelength by the first color conversion layer 510 or the second
color conversion layer 520 so that the top of the backlight unit
200 may emit the white light.
[0079] As will be described later, since the first color conversion
layer 510 and the second color conversion layer 520 have patterns,
it is possible to emit more uniform white light from the top of the
backlight unit 200.
[0080] Hereinafter, the function and shape of the first color
conversion layer 510 will be described in detail with reference to
FIGS. 5A to 5C.
[0081] FIGS. 5A to 5C illustrates a first color conversion layer of
a backlight unit according to embodiments of the present
disclosure.
[0082] Referring to FIG. 5A, the first color conversion layer 510
may be disposed in the entire area on the reflective layer 400.
[0083] Referring to FIG. 5B, the first color conversion layer 510
may be disposed in a partial area on the reflective layer 400.
[0084] When the first color conversion layer 510 is disposed in a
partial area on the reflective layer 400, the first color
conversion layer 510 may be disposed surrounding the hole 325 in
which the plurality of light sources 300 are disposed. In addition,
the first color conversion layer 510 may have a pattern, having a
large size in an area close to the plurality of light sources 300
and a small size in an area far from the plurality of light sources
300.
[0085] When the plurality of light sources 300 are disposed in the
circular hole 325, the first color conversion layer 510 may be
formed in a ring shape surrounding the hole 325.
[0086] In addition, the first color conversion layer 510 may be
formed in a pattern including two or more rings 512 and 514
surrounding the circular hole 325. In FIG. 5B, it is shown that the
first color conversion layer 510 includes only two rings 512 and
514, but may include three or more rings. In addition, the two or
more rings 512 and 514 of the first color conversion layer 510 may
have different widths from each other. For example, the width of
the first ring 512 close to the hole 325 may be larger than the
width of the second ring 514 far from the hole 325.
[0087] The first color conversion layer 510 has the effect of
supplying uniform white light to the top of the backlight unit 200
by including a pattern in which the width of the first ring 512
close to the hole 325 is larger than the width of the second ring
514 far from the hole 325.
[0088] Specifically, the closer to the light source 300, the larger
the amount of light reflected by the light blocking pattern 260 and
reaching the top surface of the reflective layer 400, so the width
of the first ring 512 surrounding the hole 325 may be larger. In
addition, the farther from the light source 300, the smaller the
amount of light reflected by the light blocking pattern 260 and
reaching the top surface of the reflective layer 400, so the width
of the second ring 514 surrounding the hole 325 may be smaller.
[0089] As the rings 512 and 514 having different widths depending
on the distance to the hole 325 is disposed on the reflective layer
400, material cost for the first color conversion layer 510 may be
reduced.
[0090] In addition, as a portion of the top surface of the
reflective layer 400 is exposed between the plurality of rings 512
and 514, a yellowish phenomenon of light emitted to the top of the
backlight unit 200 may be alleviated.
[0091] Specifically, there may occur the yellowish phenomenon in
which most of the blue light emitted from the light source 300 is
color converted by the first color conversion layer 510, and
yellowish white light is emitted to the top of the backlight unit.
In this case, by exposing both the reflective layer 400 between the
plurality of rings 512 and 514 of the first color conversion layer
510, and the reflective layer 400 from the outermost ring 514,
there may be supplied the white light which matches the ratio of
blue light, red light, and green light emitted to the top of the
backlight unit 200.
[0092] Referring to FIG. 5C, the first color conversion layer 510
may be disposed as a dot pattern in which a plurality of dots
extending radially from the hole 325 are included. The dot pattern
may include two or more dots 516 and 518 having different sizes,
and the size of the dots 516 and 518 may decrease as the distance
from the hole 325 increases.
[0093] Specifically, the closer to the light source 300, the larger
the amount of light reflected by the light blocking pattern 260 and
reaching the top surface of the reflective layer 400, so the size
of the dot may be larger. In addition, the farther from the light
source 300, the smaller the amount of light reflected by the light
blocking pattern 260 and reaching the top surface of the reflective
layer 400, so the size of the dot may be smaller.
[0094] As the dots 516 and 518 having different sizes depending on
the distance to the hole 325 are disposed on the reflective layer
400, material cost for the first color conversion layer 510 may be
reduced.
[0095] In addition, as a portion of the top surface of the
reflective layer 400 is exposed between the plurality of dots 516
and 518, a yellowish phenomenon of light emitted to the top of the
backlight unit 200 may be alleviated.
[0096] The second color conversion layer 520 will be described in
detail with reference to FIGS. 6A to 6C.
[0097] FIGS. 6A to 6C illustrates a second color conversion layer
of a backlight unit according to embodiments of the present
disclosure.
[0098] Referring to FIGS. 2 and 3 again, the second color
conversion layer 520 may be disposed on any one of the top or
bottom surfaces of the plurality of light blocking patterns 260.
The second color conversion layer 520 may be disposed in a region
corresponding to the plurality of light blocking patterns 260.
[0099] The second color conversion layer 520 may be formed by
printing on the light blocking pattern 260, for example, when using
resin ink including a plurality of KSF phosphors. The light
blocking pattern 260 may be disposed on the transparent film 250,
and the second color conversion layer 520 may be disposed on the
light blocking pattern 260.
[0100] In addition, the second color conversion layer 520 may be
formed by printing on the transparent film 250. In addition, the
light blocking pattern 260 may be disposed on the second color
conversion layer 520. The second color conversion layer 520 may be
disposed on the transparent film 250, and the light blocking
pattern 260 may be disposed on the second color conversion layer
520.
[0101] Referring to FIGS. 6A to 6C, an example in which the light
blocking pattern 260 is disposed on the transparent film 250 and
the second color conversion layer 520 is disposed on the light
blocking pattern 260 is described below. However, the present
disclosure is not limited to the above embodiment.
[0102] Referring to FIG. 6A, the second color conversion layer 520
may be disposed in the entire area or a partial area of the light
blocking pattern 260. When the second color conversion layer 520 is
disposed only in the partial area on the light blocking pattern
260, the center of the second color conversion layer 520 and the
center of the light blocking pattern 260 may coincide.
[0103] The second color conversion layer 520 is disposed on either
the top surface or the bottom surface of the light blocking pattern
260, so that the wavelength of a part of the light emitted upward
without being reflected by the light blocking pattern 260 may be
converted.
[0104] Further, since the second color conversion layer 520 is
disposed on the bottom surface of the light blocking pattern 260,
the wavelength of a part of light reflected by the light blocking
pattern 260 may be converted. Accordingly, compared to the case
where only the first color conversion layer 510 is disposed on the
reflective layer 400, the amount of light whose wavelength is
converted may increase.
[0105] Referring to FIG. 6B, the second color conversion layer 520
may include a center pattern 522 filled in and a peripheral pattern
524 surrounding the center pattern 522.
[0106] The center pattern 522 may be disposed on a substantially
vertical line with the light source 300, and may be a circular
pattern filled with the inside. Since the center pattern 522 is
filled inside, the wavelength of light emitted from the light
source 300 on the substantially vertical line may be converted.
[0107] In other words, since the amount of light directed directly
above the light source 300 is the largest, the center pattern 522
of the second color conversion layer 520 disposed directly above
the light source 300 includes a pattern filled with the inside,
thereby easily converting color even a large amount of light. As a
result, white light may be emitted to the top surface of the
backlight unit 200.
[0108] That is, according to embodiments of the present disclosure,
by having the pattern filled with the inside of the center pattern
522, it is possible to alleviate a phenomenon in which bluish light
is emitted to the top surface of the backlight unit 200.
[0109] In embodiments of the present disclosure, by forming the
peripheral pattern 524 surrounding the center pattern 522, the
wavelength of some of the light that passes through the light
blocking pattern 260 and emitted to the top surface, and some of
the light reflected by the light blocking pattern may be
converted.
[0110] According to of the present disclosure, by forming the
center pattern 522 and the peripheral pattern 524, respectively, it
is possible to reduce the material cost required to form the second
color conversion layer 520.
[0111] In addition, the peripheral pattern 524 may be formed in a
ring shape surrounding the center pattern 522 so as to evenly emit
white light to the top surface of the backlight unit 200.
[0112] Referring to FIG. 6C, the second color conversion layer 520
may include a center pattern 522 filled in and a dot-shaped
peripheral pattern 524 surrounding the center pattern 522. The
center pattern 522 may be a circular pattern filled with the
inside, and the peripheral pattern 524 may be a pattern including a
plurality of dots smaller than the size of the center pattern 522.
Each dot may be a circular dot filled with the inside.
[0113] In this case, each of the plurality of dots of the
peripheral pattern 524 may be smaller than the size of the center
pattern 522.
[0114] Since the peripheral pattern 524 is formed of a plurality of
dot patterns surrounding the center pattern 522, white light can be
evenly emitted to the top surface of the backlight unit 200.
[0115] According to embodiment of the present disclosure, since the
color conversion layer 500 may provide the backlight unit 200 that
emits high-quality white light without using an expensive color
conversion sheet, the manufacturing cost of the backlight unit 200
may be reduced.
[0116] FIG. 7 illustrates another example of a structure of a
backlight unit included in the display device according to
embodiments of the present disclosure.
[0117] Referring to FIG. 7, the backlight unit 200A according to
embodiments of the present disclosure includes a printed circuit
230, a plurality of light sources 300 disposed on the printed
circuit 230, a transparent film 250 disposed above the plurality of
light sources 300 and spaced apart from the light sources 300, a
plurality of light blocking patterns 260 disposed on at least one
of the top and bottom of the transparent film 250 and corresponding
to each of the plurality of light sources 300, a first color
conversion layer 510 disposed on at least a partial area among an
area at which the plurality of light sources 300 are not disposed
on the printed circuit 230, and a second color conversion layer 520
disposed on at least one of the top and bottom surfaces of the
plurality of light blocking patterns 260.
[0118] The first color conversion layer 510 may be directly
disposed on the printed circuit 230. In this case, a separate
reflective layer may not be interposed between the first color
conversion layer 510 and the printed circuit 230.
[0119] It will be apparent to those skilled in the art that various
modifications and variations can be made in the back light unit and
the display device of the present disclosure without departing from
the technical idea or scope of the disclosure. Thus, it is intended
that the present disclosure cover the modifications and variations
of this disclosure provided they come within the scope of the
appended claims and their equivalents.
* * * * *